Positive terminalThe raised-button end. It is part of the steel can.
Steel canIt holds everything in. It also connects the cathode to the positive terminal.
Cathode (manganese dioxide)A paste of manganese dioxide and carbon. It is the positive electrode.
SeparatorIt keeps the two electrodes from touching but lets ions through.
Anode (zinc powder)Zinc powder in a gel made with the electrolyte. It is the negative electrode.
LabelA plastic film round the can. It carries the printing and insulates the can.
SealA plastic seal across the open end. It keeps the electrolyte in.
Negative terminalThe flat end of the cell. A pin joins it to the zinc.
How this list was compiled: Every name and fact checked on 2026-10-01, a name kept only where two independent sources use it. (1) Wikipedia, text only: Alkaline battery (Construction), https://en.wikipedia.org/wiki/Alkaline_battery, and Dry cell, https://en.wikipedia.org/wiki/Dry_cell (steel can as the cathode connection; cathode of manganese dioxide with carbon; separator lining the hollow of the cathode; zinc powder in a gel with the potassium hydroxide electrolyte; plastic gasket; outer wrap; raised button positive, flat end negative; a dry cell has no free liquid). (2) A battery maker's alkaline manganese dioxide handbook, https://data.energizer.com/pdfs/alkaline_appman.pdf (cutaway of a cylindrical cell: cathode, anode, separators, steel can, brass collector, positive and negative covers, plastic film label, nylon seal). (3) University of Cambridge, DoITPoMS teaching package Batteries, https://www.doitpoms.ac.uk/tlplib/batteries/printall.php (zinc powder anode, manganese dioxide cathode outside it, potassium hydroxide electrolyte, separators; the zinc-carbon cell for comparison). (4) For a cell and a battery: Explain that Stuff, Batteries, https://www.explainthatstuff.com/batteries.html, and Wikipedia, Series and parallel circuits (two cells in series give 3 volts). Licence: own work
The drawing: Drawn for this site on 2026-10-01 from plain geometry; nothing traced. Licence: own work
How it works
This is the kind of cell that goes in a flashlight, cut down the middle. Tap a numbered ring to see what each layer is called, or press Quiz me.
Read the full guide
From the outside in
A printed label wraps a steel can, and the raised button on the can is the positive terminal. Pressed against the inside of the can is the cathode, a paste of manganese dioxide and carbon. A thin separator lines it. The middle is the anode: zinc powder in a gel made with the electrolyte, potassium hydroxide. A brass pin runs up the center of the zinc and joins it to the flat negative terminal. A plastic seal closes the open end.
It is called a dry cell because it holds no free liquid, so it works any way up without spilling.
Questions and answers
What are the parts of an alkaline dry cell?
A steel can with the positive terminal on its closed end, a manganese dioxide cathode, a separator, a zinc powder anode with a metal pin up its center, a seal, a flat negative terminal and a label round the outside.
Why is it called an alkaline battery?
Its electrolyte, potassium hydroxide, is an alkali. The older zinc-carbon dry cell uses a paste of ammonium chloride instead.
How is an alkaline cell different from a zinc-carbon dry cell?
It is built inside out. In a zinc-carbon cell the zinc is the outer case. In an alkaline cell the zinc is a powder in the middle and the manganese dioxide cathode is on the outside, against a steel can.
What is the difference between a cell and a battery?
A cell is the basic unit, with two electrodes and an electrolyte. A battery is one or more cells joined together. Two 1.5 volt cells joined end to end, in series, give 3 volts.